the science of sealing attic wall headers
Find my posts, which I now review and extend. Pick Label: Sealing Wall Headers , here or at the right.
I think the process of heat transfer at attic walls, via paths at wall headers in an attic, can be imagined with this captioned photo:
Always in my work, wall headers are 100% sealed with flexible grout, as they are revealed. Gaps as here, are sometimes very large. Blackness of insulation pushed to the right speaks of the heat transfer process, now blocked by the sealing. Energy in convection pulls air down in some wall areas, and up in others, attempting to equalize attic and wall interior temperature. Dirt of outside air is deposited where passage is down, in the constant churn of air. The process has nothing to do with air infiltration, but rather is throttled action of attic floor pits.
The process in any home shifts with room use and weather outside. No one has attempted rigorous analysis or testing, or should. Yet, we need to estimate the benefits of sealing in defense of the fair cost of sealing, $200 to $500 in any home.
I estimate the savings as that of an inefficient attic floor pit, 10% bare area equivalent , of conditioned space ceiling area.The home of the photo above has 1366 sf heated space, and I charged a meager $200 for the 100% sealing with my flexible grout.
Estimated savings are $2.4*0.1*1366/3 = $109 per year. Two year simple payback. Bases of the math are: heating with a gas furnace 88% efficient, 4400 65° HDD, natural gas at real cost $2 per therm. I wish for math to show that annual savings are at least 20% of the $200 cost. That is achieved, however you do the math, and whatever you think is fair cost of energy.
Recovery of invoiced cost could never be achieved if the home owner had hired the top HPwES contractor in Portland, Oregon:
This bid is mean. It is knowingly based on lies. It is criminal. Allowed and encouraged criminal conduct kills public trust and kills weatherization activity.
Failure to do 100% sealing of attic floors must be seen as inexcusable. Excuses are offered by powers in Portland, Oregon, that consequences are not measurable by a blower door , and methods tried are rejected by nearly all contractors Final Evaluation Report - New Homes Air Sealing Pilot . In a state of confusion, lacking conviction through scientific understanding, air sealing does not happen. None is required.
There is no longer an Energy Trust incentive for sealing air leaks in single-family homes in Oregon.
And yet, in Oregon, the phony blower door purveyors of Home Performance with Energy Star , have large rewards from public funds, that are denied to a true believer in home sealing. This in effect is a conscious and very great harm against me, where my superior work is acknowledged, as I forswear blower door madness. It is an action of Gresham's Law , even though the rewarded competition charge ruinously in their fraud. Usually, with counterfeit, good is ruined because it is less profitable to the public. Here, where outrageous cost prevails, it can only be within privileges offered to complicit businesses; the public is not in on it, and all will tumble, soon.